Utilization of the heat content of hot residual liquors



May 23, 1939. R Z 2,159,899

UTILIZATION OF THE HEAT CONTENT OF HOT RESIDUAL LIQUORS Filed Oct. 10, 1936 lm/en for UNITED STATES PATENT OFFICE UTILIZATION OF THE HEAT CONTENT OF HOT RESIDUAL LIQUOR-S Bertold Mannheim-Waldhof, Germany,

assignor of one-half to Zellstofliabrik Waldhof, Mannheim-Waldhof, Germany Application October 10, 1936, Serial No. 105,093 a In Germany November 28, 1935 1 Claim. (01. 202-49) This invention relates to the utilization of the heat content of residual liquors. It has already been proposed to utilize the residual liquor for preheating mash, for instance by passing it though a preheater, through the tube system of which the mash flows. The heat is thus used again indirectly.

It has also already been proposed to utilize the heat content of the residual liquor directly in the distillation apparatus, by withdrawing by suction the vapours which develop from the residue, when expanding in a separate pressure release vessel by means of a separate suction device, for instance by means of a compressor, out ofthe I pressure release vessel 'and, after compression,

conveying them to the distillation apparatus.

has also been proposed to arrange a plurality of such pressure release vessels in series and to provide a corresponding .number of compressors.

The sucked-off and compressed vapours resulting from the pressure release were then introduced separate from the live steam into the distillation vessel.

It has been found, however, that in this way it is not possible to recover the waste heat of the liquor in a manner which satisfies both economical and technical requirements. Owing to the complicated constructionof the apparatus there is the possibility of the occurrence of heat losses, which may in certain circumstances be considerable, and of disturbances in the operation of the apparatus.

These disadvantages may be avoided and a completely satisfactory utilization of the heat content of the residual liquorobtained, by driving the heat pump, by means of which the vapour, formed in the pressure release vessel are withdrawn,-with the live steam for heating the distillation apparatus and by conveying the said live steam to the distillation apparatus together with the withdrawn vapours. As the heat pump, an injector, a compressor of a known type or the like may be used.

This mode of operation is particularly simple 45 as regards the method and the apparatus employed. This ensures a completely satisfactory and reliable control and furthermore there isa more complete utilization of the heat content of the residual liquor, as, owing to the more simple 50 construction of the apparatus, heat losses connot 5'5 from the following. Whereas in the hitherto The considerable simknown methods of conveying the vapours withdrawn by suction from the pressure release vessel into the distillation apparatus in addition to the supply of live steam a separate source of power is required, in the new method the increased consumption of energy for the double supply and also the cause of many sources of trouble are removed by only a single source of power being used, since both the supplying of the live steam and the withdrawal by suction of the vapours resulting from the pressure release and their conveyance to the distillation vessel are efiected by the heat pump.

The saving in steam effected by the mode of operation according to the invention is considerable in certain circumstances. It is greater, the higher the pressure of the live steam employed. Whilst, for instance, with a live steam pressure of 2 atmospheres the saving in steain amounts as a rule to lessthan 10%, with a pressure of 6 atmospheres the saving in steam will be about The accompanying drawing illustrates one constructional example of the invention.

' To the distillation apparatus A heating stea is fed through: the pipes I andZ. In these supply pipes is interposed an injector B, the suction branch of which is in communication through the -pipe.3 with the pressure release vessel C, preferably with the upper part thereof, whereby a partial vacuum is produced in C. The vapour resulting from the pressure release develops in the vessel C in accordance with the reduction in temperature accompanying this partial vac-- uum and the consequent giving ofl of heat by the residual liquor which flows through the pipe 4 out of the distillation apparatus A to the pressure release vessel C. Through the pipe 5 the residual liquor relieved of pressure is then conveyed into the open. The vapour resulting from from the fractionator, removing a bottom stream consisting practically exclusively of heavy material for the fractinnatnr intrnducinl the bottom ing efiected by live steam but without any supply of additional heat to the bottom stream in the pressure release zone, and using the live steam I together with the evacuated vapours for heating the material to be distilled.

IBERTOLD KRANZ. 

